Land of the Rising Water

The 2002 World Cup final was played in a stadium built on pillars over a swamp. Yokohama used to be one of the world's most flood prone cities. Like the nearby Japanese capital Tokyo, it's built on a flood plain. Japan is a world leader in civil engineering to control flooding and conserve wetlands. As the venue for the 3rd World Water Forum, it's fitting that the Changing Currents season kicks off with coverage of how the host country is managing its water.

In Tokyo, 30 million people are building their future on the flood plain.

In June 2002 all eyes were on the Yokohama stadium, Japan, for the World Cup Final. Behind the scenes, engineers had made sure nothing would stop the game; the stadium was built on stilts. In this densely packed country, most people live in flood prone areas, and while they may be relative newcomers to football, the Japanese have a long history of water management. 400 years ago they built a clean drinking water supply for a city of a million people. With fresh water one of the major global resource issues of the 21st century, the technologies developed in Japan may lead to innovative solutions for urban water supply and management around the world. Earth Report travels to Japan to take a look at both grand and modest schemes designed to cope with water supplies and flood controls.
 

Flood Control: Diverting Rivers and Building Channels

Japan is a country inherently prone to flooding. Annual monsoon rains drench the alluvial plains that stretch down to the sea, threatening populated areas with serious flooding.

The Japanese have built elaborate defences in the upper, middle, and lower reaches of the rivers that flow by Tokyo on the Kanto Plain. In the mountainous upper reaches there are a series of dams. The dams have multiple functions; they provide flood control, they supplement Tokyo's water supply in the dry season, and they generate electricity. In the middle reaches canals divert water from the river into irrigation for agriculture and to water treatment plants that clean water for houses and industry. Dikes protect homes and businesses along the rivers and canals. And there is a massive retaining basin built to prevent flooding. It's partly a constructed wetland providing habitat for plants and animals, and a perfect hiking ground.

In a further effort to prevent flooding, a 6.5 kilometre long underground channel costing around US$2 billion and acting as a reservoir is being built deep in the bowels of the Earth beneath Tokyo.
 

Managing Water in Ancient Edo

The Japanese are old hands at water management. 400 years ago the Tokugawa Shogun built Edo as his capital which is where modern Tokyo now stands. At a time when people in Europe were dying from water-borne diseases, Japan had already built a clean water system for a city of over a million people. This system, the "Tamagawa Josui" was still in use in Tokyo in the early 1960s.

Sumiko Enbutsu is a historian and an author. She has documented the historic waterways of ancient Edo. Together with Mimi Le Bourgeois she has published two books popularising historic walks along Tokyo's traditional waterways.
 

Community Action at Lake Kasimigaura

The most widespread pollution in Tokyo comes from organic waste from millions of toilets and kitchens. This waste enriches the water and causes excessive growth of algae. The algae absorb the oxygen in the water killing other aquatic life. At Lake Kasimigaura enriched water has damaged the lake. In support of government efforts, the Lake Kasimigaura citizen association has taken on the goal of making the lake safe for swimming by 2020. The group consistently monitors the water quality, taking measurements in the lake itself and in all the streams feeding the lake so that they can pinpoint the sources of pollution. At the edge of the lake the community has built a bio-park to clean their household waste water before it enters the lake. At the nearby community centre citizens promote new ways to cut enrichment, such as making fertiliser from used cooking oil rather than pouring it down the drain.
 

Collecting Rainwater in the Concrete Jungle

Tokyo is a concrete jungle. Natural rainfall cannot even infiltrate the soil because most of the land has been paved over. Although water is badly needed in Tokyo, rain that falls on Tokyo has always been treated as a nuisance because of the danger of flooding.

The success or failure of 21st century mega-cities will depend in large part on how we deal with water.

Professor Murase wanted all new buildings in the Sumida River district to be built so that they could catch all the rainwater that fell on them. The new Edo Museum and the National Sumo Stadium, both huge buildings, complied. The rainwater collected can be used for flushing toilets and watering plants, and in emergencies it can also be used as drinking water.

Nabuo Tokunaga is leading individual citizens to join the rainwater harvesting efforts. He worried that earthquakes would endanger the neighbourhood, and that at the very time water was needed to fight fires, the water mains would be cut off. Inspired by examples from ancient Edo he designed small-scale rainwater harvesting systems that individuals can install in their homes.
 

The Sumida Salmon Club: New Hope for New Generations

Some Tokyo residents have begun to take steps back towards nature. 83 year old Hiromichi Yanagisawa and his friends have created a club dedicated to reintroducing salmon to the Sumida River.

Getting the next generation to understand and participate in clean water efforts is the goal of Mr. Yanagisawa. The Sumida Salmon Club initiated contact with a remote village in northern Japan and Mr. Yanagisawa joined in community harvesting of salmon roe. Together with his friends and neighbours he distributes fertilised salmon eggs to schools in the area. The school's children then study the life cycle of the salmon as they raise salmon fry and ultimately release them in the hope of reintroducing salmon to the Sumida River. While the chances of salmon returning are remote, there is little doubt that young people can be fascinated and inspired by the nature of life and that the choices they make in the future will be informed by this experience.
 

Tokyo Alarm Bells

Tokyo has spent billions of dollars on its urban water management system, but the power of nature still represents a very real threat to the system. In order to ensure the safety of the people on the flood plain, Tokyo is pioneering one of the most advanced alert systems in the world. The Foundation for River and Basin Integrated Communications (FRICS) is a publicly funded organisation that collects all available radar and river level data and then provides graphic interpretations to the emergency services and the public via the internet and directly to 3rd generation mobile phone subscribers.
 

Hi Tech, Lo Tech

Tokyo is one prototype of the modern metropolis. At huge cost, an unprecedented number of water projects have been built. Is this the way forward for growing cities elsewhere? Many developing countries don't have the money to build the big scale water projects that Tokyo has, but as illustrated in this Earth Report, some of the best designs cost almost nothing and can work anywhere.

Only 1% of the world's water is drinkable. With the world's population at over 6.2 billion and rising the pressure on fresh water from people, pollution and extreme weather is intense. Nowhere is the pressure greater than in large, densely populated cities.

In March 2003 the Third World Water Forum is meeting to discuss water issues on a global level.